.\" Copyright (c) 2003 Bruce M. Simpson. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" .\" THIS SOFTWARE IS PROVIDED BY Bruce M. Simpson ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL Bruce M. Simpson BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" $FreeBSD: src/lib/libc/net/getifmaddrs.3,v 1.3.22.1.4.1 2010/06/14 02:09:06 kensmith Exp $ .\" .Dd November 14, 2003 .Dt GETIFMADDRS 3 .Os .Sh NAME .Nm getifmaddrs .Nd get multicast group memberships .Sh SYNOPSIS .In sys/types.h .In sys/socket.h .In ifaddrs.h .Ft int .Fn getifmaddrs "struct ifmaddrs **ifmap" .Ft void .Fn freeifmaddrs "struct ifmaddrs *ifmp" .Sh DESCRIPTION The .Fn getifmaddrs function stores a reference to a linked list of the multicast memberships on the local machine in the memory referenced by .Fa ifmap . The list consists of .Vt ifmaddrs structures, as defined in the include file .In ifaddrs.h . The .Vt ifmaddrs structure contains at least the following entries: .Bd -literal struct ifmaddrs *ifma_next; /* Pointer to next struct */ struct sockaddr *ifma_name; /* Interface name (AF_LINK) */ struct sockaddr *ifma_addr; /* Multicast address */ struct sockaddr *ifma_lladdr; /* Link-layer translation, if any */ .Ed .Pp The .Va ifma_next field contains a pointer to the next structure on the list. This field is .Dv NULL in last structure on the list. .Pp The .Va ifma_name field references an .Dv AF_LINK address structure, containing the name of the interface where the membership exists. .Pp The .Va ifma_addr references the address that this membership is for. .Pp The .Va ifma_lladdr field references a link-layer translation for the protocol-level address in .Va ifma_addr , if one is set, otherwise it is .Dv NULL . .Pp The data returned by .Fn getifmaddrs is dynamically allocated and should be freed using .Fn freeifmaddrs when no longer needed. .Sh RETURN VALUES .Rv -std getifmaddrs .Sh ERRORS The .Fn getifmaddrs may fail and set .Va errno for any of the errors specified for the library routines .Xr malloc 3 or .Xr sysctl 3 . .Sh SEE ALSO .Xr sysctl 3 , .Xr networking 4 , .Xr ifconfig 8 .Sh HISTORY The .Fn getifmaddrs function first appeared in .Fx 5.2 . .Sh BUGS If both .In net/if.h and .In ifaddrs.h are being included, .In net/if.h .Em must be included before .In ifaddrs.h .